Marty, the Russian blue who served as the inspiration for the rainbow pop-tart awesomeness of online sensation Nyan Cat, has passed away Feline Infectious Peritonitis. Marty's owner -- and creator of Nyan Cat -- Chris Torres announced the sad news on Nov. 1st:

"Even with the medical treatment he received he still deteriorated quickly. I’ve been force feeding him and keeping him warm for three days. For a while today it looked like he was getting better, but unfortunately, at around 9pm tonight he got convulsions and passed on my arms. I will really miss Marty. He was seriously just the coolest cat ever. I just couldn’t save him."